The purpose of this K18 career enhancement award is to provide mentored research experience, and career enhancement and education activities necessary for the applicant's transition to comparative effectiveness (CE) and patient-centered outcomes research (PCOR) in pediatric chronic disease as a local and national methodology expert. The applicant is an established independent statistical method researcher and successful biostatistician with many years of clinical trial experience, and has extensively collaborated in pediatric inflammatory bowel disease (IBD) including pediatric onset Crohn's disease (CD). She is at the cusp of this transition in order to attain her career goal of improving the quality of evidentiary information by enhancing the quantitative analysis of CER at both population and individual patient levels. This career goal arose from her collaborations in pediatric IBD, where the lack of CE evidence leads to a huge variation in care and management practice and little or no improvement in outcomes has observed over the past four decades despite therapeutic advances. Pediatric IBD, like many pediatric chronic conditions, meets the NIH definition for a rare disease for which collaborative research networks and their registry data play a critical role. Pooling the cohorts of multiple registries will increase statistical powr and external validity. However, registries differ from one another and the discrepancies, if not sufficiently addressed, may threaten the validities of studies. The applicant proposes training/education activities fundamental to CER/PCOR and a research project that aims to answer the timing of biologics CE question in pediatric onset CD by combining two pediatric IBD network registries. The two registries contrast each other in their patient/provider population bases, and breadth and depth of data they collect, which poses an array of methodological challenges. The conduct of the proposed research will be monitored by a strong mentoring team that includes a registry related patient centered outcomes research expert, a clinical content expert and an established epidemiology and will properly train the applicant about multi-registry CE studies. The research question of timing of biologics introduction is one of the Institute of Medicine (IOM)'s top 25 priorities for CER. This study will provide the currently lacking CE information of biologics, which will enable all stakeholders to more objectively assess the tradeoffs of cost versus benefit or effectiveness versus safety of the therapies, and facilitate th decision making. Leveraging the knowledge, skills and professional enhancement afforded by this K18, the candidate will be well poised to serve as a CER/PCOR method expert both locally and nationally, particularly in pediatrics chronic disease areas.